0325 GMT (11:25 p.m. EDT Tues.)
An Orbital Sciences Corp. Antares rocket making only its fifth flight exploded seconds after launch from the Virginia coast Tuesday, erupting in a spectacular fireball and destroying an uncrewed Cygnus cargo ship in a disheartening failure for NASA’s commercial space station resupply program.

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0140 GMT (9:40 p.m. EDT Tues.)
"But I can assure you we will find out what went wrong and we will correct it and will fly again," Culbertson says.
0130 GMT (9:30 p.m. EDT Tues.)
"What we know so far is pretty much what everyone saw on the video. The ascent, there was some, let's say, disassembly of the first stage it looked like and the vehicle fell to Earth," said Frank Culbertson. "We don't have any early indications of what might have failed."
0120 GMT (9:20 p.m. EDT Tues.)
"Launch is a really tough business," said Bill Gerstenmaier, associate administrator of NASA's Human Exploration and Operations Mission Directorate.

Orbital will lead the investigation with the FAA and NASA.

The crew of the International Space Station is in no danger and there was no critical consumables lost in the mishap.

There were no injuries on the ground from the mishap, said Frank Culbertson, executive vice President and general manager of Advanced Programs Group at Orbital Sciences Corp.

The problem will be investigated and flights will resume, Culbertson said. The data is being looked at by investigators already. The crash scene will be opened to teams at daybreak.

If any of the local residents find any debris, they are urged to call 757-824-1295.

2350 GMT (7:50 p.m. EDT)
The post-failure news conference is scheduled for 8:30 p.m. EDT.
2340 GMT (7:40 p.m. EDT)
A gallery of photos from the failure is posted here.

A video of the ill-fated flight is posted here.

2335 GMT (7:35 p.m. EDT)
A post-failure news conference is not expected before 8 p.m. EDT (0000 GMT). Orbital Sciences is in the process of impounding the data and telemetry from tonight's launch for the investigation that will involved several government agencies. There were no injuries reported.
2123 GMT (6:23 p.m. EDT)
Contingency operations are in effect. Damage appears contained to the launch pad itself.
2122 GMT (6:22 p.m. EDT)
2122 GMT (6:22 p.m. EDT)
LIFTOFF of the Antares rocket with the "Deke Slayton" Cygnus cargo craft, resupplying the International Space Station with provisions and experiments.
2122 GMT (6:22 p.m. EDT)
T-minus 5 seconds. Transporter erector is swinging back. Standing by for ignition!
2122 GMT (6:22 p.m. EDT)
T-minus 15 seconds. The engine steering check is underway.
2121 GMT (6:21 p.m. EDT)
T-minus 60 seconds. High speed video cameras are activating.
2121 GMT (6:21 p.m. EDT)
T-minus 90 seconds.
2120 GMT (6:20 p.m. EDT)
T-minus 2 minutes. Flight computer is ready. The rocket's propellant tanks are pressurizing now.
2119 GMT (6:19 p.m. EDT)
In the next few moments, the Antares first stage's propellant tanks will pressurize for flight, and computers will monitor the rocket and ground system parameters to ensure everything is ready for liftoff.

At T-minus 15 seconds, the two AJ26 first stage engines will swivel at the base of the rocket to ensure they can steer the launch vehicle in flight.

At T-minus 5 seconds, the transporter-erector-launcher will retract away from the rocket, leading to ignition of the AJ26 engines as clocks hit zero.

Liftoff will occur 2 seconds later after computers verify the engines are running normally.

2118 GMT (6:18 p.m. EDT)
T-minus 3 minutes, 30 seconds. The auto sequence has started.
2118 GMT (6:18 p.m. EDT)
T-minus 4 minutes and counting. The automatic countdown sequence begins in a few seconds.
2117 GMT (6:17 p.m. EDT)
T-minus 5 minutes and counting. The rocket is now running on its own battery system.
2116 GMT (6:16 p.m. EDT)
T-minus 6 minutes and counting. The Antares rocket's avionics will be switched from external power to an on-board battery in about one minute.
2115 GMT (6:15 p.m. EDT)
T-minus 7 minutes and counting. The liquid oxygen tank is full. The transporter erector is armed for rapid retract in the final seconds of the countdowm.
2114 GMT (6:14 p.m. EDT)
T-minus 8 minute and counting. No problems are reported in the countdown and the weather continues to look favorable for liftoff at 6:22:38 p.m. EDT.
2212 GMT (6:12 p.m. EDT)
T-minus 10 minutes and counting. The next step in the engine chilldown procedure is now beginning. And final vehicle arming is underway.
2211 GMT (6:11 p.m. EDT)
T-minus 11 minutes and counting. The final prelaunch poll of the Antares team confirms all positions are ready for the final phase of the countdown.
2209 GMT (6:09 p.m. EDT)
T-minus 13 minutes and counting. The roughly five-ton Cygnus spacecraft, christened the "Deke Slayton" after the Mercury Seven astronaut, is running on internal power and is in good shape for launch.
2207 GMT (6:07 p.m. EDT)
The Cygnus spacecraft will reach the International Space Station on Nov. 2 after launch tonight.
2206 GMT (6:06 p.m. EDT)
T-minus 16 minutes and counting. Another poll is coming up at T-minus 12 minutes to approve the start of a medium-flow chilldown, another step to condition the main engines for ignition.
2205 GMT (6:05 p.m. EDT)
The Antares launch team continues stepping through countdown procedures toward liftoff at 6:22:38 p.m. EDT (2222:38 GMT).
2203 GMT (6:03 p.m. EDT)
Upper level winds are reported favorable for launch.
2202 GMT (6:02 p.m. EDT)
T-minus 20 minutes and counting.
2201 GMT (6:01 p.m. EDT)
Today's launch will fly southeast from Wallops Island, Va. Communications sites in Virginia, North Carolina and Bermuda will track the rocket during its 10-minute flight, along with support from NASA's Tracking and Data Relay Satellite System.

Check out a timeline of key events during the launch.

Earlier updates